A federal judge on Wednesday enjoined the U.S. Patent and Trademark Office from instituting new rules, scheduled to take effect Nov. 1, that critics say would limit the level of patent protection available to inventors.

Ruling on a motion filed by pharmaceutical company GlaxoSmithKline, which is suing the Patent Office over the issue, Judge James Cacheris of the U.S. Court for the Eastern District of Virginia blocked, for now at least, the patent office from implementing the regulations Thursday as planned.

"This is a sign that the challenge to these rules is legitimate," said Mark Murphy, a Chicago-based patent attorney whose firm, Cook Alex, is not involved in the litigation.

The new rules are intended to speed patent reviews by the chronically understaffed USPTO. Among other things, they limit so-called "continuing applications" through which inventors can modify existing patent applications.

Murphy said the new rules would "severely limit the level of patent coverage you can get for an invention" if they are allowed to take effect.

GlaxoSmithKline originally filed its suit against the USPTO on Oct. 9.

The drug manufacturer contends that it, and other companies that invest heavily in research and development, needs the freedom to broaden their patent claims when new applications for their inventions are discovered.

A spokesperson for the patent office said the USPTO is committed to implementing the new rules despite Wednesday's setback.

"The USPTO continues to believe that the rules are an important component of modernizing the patent system. They are part of a package of initiatives designed to improve the quality and efficiency of the patent process," said the spokesperson.